Rig Time Optimization During Workover by Predefined Well Integrity Criteria Using MAASP Sensitivity Analysis

Abstract

During normal rig workover operations, once the old completion is retrieved, corrosion log is being executed to check the condition of the casing and/or liner as one of the means to establish a way forward. Decision can be made easily in case of pipe found completely corroded or absolutely intact. However, such clear scenarios are not always the case and the decision making takes significant time, specially if corrosion log results are received at night time or during the week end. It may become a subject of hot discussion between involved stakeholders, trying to find a right balance between safety and operations. Therefore Gas Development Operations Subsurface Team of ADNOC Onshore requested Technical Center Well Integrity Team to identify clear criteria in advance, to save rig time and improve business performance and decision making process. Based on this request Technical Center developed a strategy of predefined well integrity criteria's that are being successfully used now, saving rig time during workover and avoiding conflicts between teams in questionable situations. The method is based on several factors: Maximum Allowable Annulus Surface Pressure (MAASP) calculation as per Norsok D10 standard, application of Double Barrier concept for Secondary Well Barrier Envelope, sensitivity analysis based on MAASP degradation and remained wall thickness of casing and/or liner. This method has already been successfully implemented in several wells during workover operations saving time for decision making. It is planned to be included in the next release of corporate procedures. Method, explained in this paper can be used as a guideline by all petroleum engineers, drilling engineers, well integrity engineers and petrophysicists who are involved in workover operations, helping them to improve decision making process based on the results of the casing corrosion logs. In addition, the subject of well life prediction and well life extension in standard Company well design is covered, with focus on safety during workover operations.